The instant invention is directed to a composite papermaking fabric formed to provide improved wearability, stability and uniform porosity.
Composite papermaking fabrics are widely used and well known throughout the papermaking industry as is illustrated by U.S. Pat. No. 5,152,326 to Vohringer and U.S. Pat. No. 5,544,678 to Barrett. In composite papermaking fabrics, which comprise upper support and lower contact fabrics, it is a primary object to protect the binding yarns or those which bind the upper and lower fabrics together, from wear. This is necessary because once a binder yarn breaks, the upper and lower fabrics separate destroying the papermaking fabric.
Traditionally, the binder yarns are protected by using smaller yarns and crossing them over the lower fabric yarns adjacent a large knuckle. This approach sometimes interferes with drainage as the binders do not form a part of the basic weave pattern of the upper and lower fabrics.
Another approach is to incorporate the binder yarns into the weave pattern of the upper and lower fabrics. This approach, while improving drainage, subjects them to increased wear. Even when they are incorporated into the weave pattern as smaller yarns, certain areas along their binding length are not protected.
Accordingly, it is an object of the present invention to provide a composite papermaking fabric with improved drainage, stability and wearability.
Another object of the instant invention is a composite papermaking fabric in which the binding yarns form a part of the basic weave pattern of the upper and lower fabrics.
Another object of the invention is the provision that the binder yarns form floats on the contact surface which are protected against wear along their entire length.
Another object of the invention is a composite papermaking fabric in which the binding yarn floats are arranged between protective floats along their entire length.
Another object of the invention is the provision of a composite papermaking fabric which is woven in a 40 pick repeating pattern.
Another object of the invention is the provision of a composite papermaking fabric which is woven in a 70 pick repeating pattern.